The present invention relates to exercise equipment and methods.
In general, exercise can be organized into two principal categories, cardiovascular and musculoskeletal. Cardiovascular exercises, such as aerobics, are quite popular. However, it is now known that cardiovascular training alone is not sufficient to obtain balanced fitness, and there is growing evidence identifying a clear need to provide for muscular and joint strength in addition to cardiovascular health.
Muscular development falls into four general types. One type is isometric contraction, which results in an increase of muscle tension while the muscle length remains constant. Typical examples of isometric muscular activity includes the flexing of the arm or pushing the hands together while the arm or hands are not moved through a range of motion. While the tension increases in the muscle, the muscle does not move.
The second type of muscle development is known as pleiometric contraction, which occurs when both the muscle tension and length increases. This type of contraction occurs in exercises such as walking down stairs or landing from a jump.
A third type of muscle activity is known as isotonic contraction, in which the muscle tension remains constant and the muscle length decreases; such muscle activity occurs in the legs during walking or running.
A fourth type of muscle activity is known as isokinetic contraction, and occurs when the muscle tension increases and the muscle length decreases. Conventional weight lifting is an example of this type of activity.
It is generally known that the best way to develop the shape, size and definition of muscles is to apply a resistance and then move the muscle through its entire range of motion from a full stretch to a full contraction and back to a full stretch (or vice versa). It is also known that to improve the strength of the bones and joints, it is necessary to move the joints through its correct plane of movement; movement through an incorrect plane may actually weaken or injure a joint, or fracture a bone.
In addition to so called "free weights" (i.e., barbells and the like) there have been developed a number of exercise machines which assist an individual in achieving isokinetic muscle exercise. These prior art machines are based on a variety of lever arm and other mechanical techniques. Some of these prior art systems have been developed to provide multiple purpose exercises for a variety of different muscles. Examples of such equipment are disclosed in the following United States patents: U.S. Pat. No. 4,951,942 to Walden; U.S. Pat. No. 4,919,419 to Houston; U.S. Pat. No. 4,907,798 to Burchatz; U.S. Pat. No. 4,826,157 to Fitzpatrick; U.S. Pat. No. 4,691,918 to Rockwell; U.S. Pat. No. 4,638,995 to Wilson; U.S. Pat. No. 4,627,614 to diAngeli; U.S. Pat. No. 4,618,144 to Gibson; U.S. Pat. No. 4,582,320 to Shaw; U.S. Pat. No. 4,576,377 to Wolff; U.S. Pat. No. 4,521,013 to Dofel, and U.S. Pat. No. 4,072,309 to Wilson. There is also disclosed in U.S. Pat. No. 4,623,267 an elastomeric bearing system for use in multiple purpose exercise apparatus, particularly of the type disclosed in U.S. Pat. No. 4,072,309 to Wilson, which is sold under the SOLOFLEX trademark. Recently, Nordictrack of Chaska, Minn. introduced an exercise system under the trademark NORDICFLEX GOLD, which system uses a straight rail and a lever arm to direct an exercise along a restricted plane.
The manner of operation of a typical lever-type prior art multiple purpose exercise system is illustrated in FIGS. 1 and 2. In one exercise known as the "bench press" shown in FIG. 1, the person exercising (designated by the letters "EP") rests upon a horizontal seat and maneuvers a lever L1 through an arc A1. With the lever under tension (for example, by the use of elastic bands as disclosed by Wilson in the aforementioned U.S. Pat. No. 4,072,309), isokinetic muscle contraction is achieved. However, because the arc A1 is displaced across the body of the exercising person EP, then different portions of the same muscle group are being utilized during the same exercise. Similarly, in using the equipment of FIG. 1 in an overhead exercise (as shown in FIG. 2), the exercising person, while operating the lever L2 under tension, is required to extend the lever L2 through an arc A2, thus also displacing the direction of exercise laterally and thereby using different muscle groups.
In U.S. Pat. No. 4,817,943, Pipasik discloses a total shoulder exercise and muscle development machine in which each forearm is placed against an arm abutment member, and then the forearms are rotated outwardly while the hands are also used to develop the shoulder by extension of a hand grip mechanism along a straight line into a spring biased cylinder.